The two will appear at a news conference after touring a Los Angeles-based solar energy company and the governor will make his endorsement official, aides said.

Schwarzenegger’s move comes as McCain plows toward the nomination, the only Republican candidate to have won three hotly contested primaries — New Hampshire, South Carolina and Florida — since voting began this month.

California offers a whopping 170 delegates to the Republican nominating convention. Candidates secure three delegates for each of the state’s 53 congressional districts they win in the primary, in which only Republicans can vote.

McCain and Schwarzenegger have been friends for years, and the two share a bond over their work on global warming issues as well as their similar independent streaks. Aides say Schwarzenegger long has respected McCain’s push to eliminate wasteful spending in Washington, protect the environment and fix a broken immigration system.

This month, Schwarzenegger told reporters he would not make an endorsement in the GOP primary. But senior advisers say his friend Rudy Giuliani’s departure from the race Wednesday changed the dynamics of the decision for Schwarzenegger, and he decided to go ahead with the endorsement once it was clear Giuliani’s candidacy was over.

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